A kinetic analysis of the effects of interleukin-2 diphtheria toxin fusion protein upon activated T cells.
The interleukin-2 diphtheria toxin-related fusion protein (IL-2 toxin) inhibits protein and DNA synthesis IN rIL-2 (10(-10) M) stimulated T lymphoblasts in a dose-dependent fashion. However, prior to target cell death very low concentrations of rIL-2 and IL-2 toxin synergistically stimulate [3H] thymidine incorporation despite inhibition of [14C] leucine uptake. A sequential analysis of [3H] thymidine incorporation shows that high IL-2 toxin concentration (10(-9)-10(-7) M) stimulates DNA synthesis at 18 hr of culture and inhibits [3H] thymidine uptake after 24 hr, while low concentrations of IL-2 toxin (10(-12)-10(-10) M) exhibits stimulatory effects only after 24 hr of culture. Anti-Tac a monoclonal antibody directed against the p55 chain of the high affinity IL-2 receptor (IL-2R) blocks the stimulatory effects of high-dose IL-2 toxin, thereby proving that these effects are mediated through the IL-2 domain of the fusion protein. At 7 hr following interaction with IL-2R receptor (IL-2R)+ T cells, IL-2 toxin-treated cells evidence augmented transcription of the heat shock protein gene, an effect indistinguishable from those mediated by rIL-2. We conclude that interaction of IL-2 toxin with IL-2R+ T cells initially mimicks the stimulatory effects of IL-2 upon gene transcription and DNA synthesis yet concomitant inhibition of protein synthesis is evident.
Walz
G
G
Charles A. Dana Research Institute, Boston, MA 02215.
Zanker
B
B
Murphy
J R
JR
Strom
T B
TB
D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D004167:Diphtheria Toxin / Q000494:pharmacology*; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology*; D008213:Lymphocyte Activation; D014176:Protein Biosynthesis; D015375:Receptors, Interleukin-2 / Q000032:analysis; D011993:Recombinant Fusion Proteins / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000187:drug effects*; D014158:Transcription, Genetic / Q000187:drug effects
D004167:Diphtheria Toxin; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D011993:Recombinant Fusion Proteins; D004247:DNA